The present invention relates to avionics and military displays and, more generally, relates to such displays which receive data from sensors having a relatively higher dynamic range.
High-performance imaging sensors typically have dynamic ranges greater than 8 bits/pixel; however, many displays limit displayable dynamic range to 8 bits/pixel.
As a result, to maintain the dynamic range advantage of these high-performance sensors, efforts have been made to find a way to effectively display the high-dynamic range of the sensor on a lower dynamic range display.
Dynamic Range vs. Bits (in dB)
8 bits is 48.2 dB.
9 bits is 54.2 dB.
10 bits is 60.2 dB.
In the past, the output of high-dynamic range video camera sensors have been mapped to lower-dynamic range displays using an assortment of look-up tables with differing mapping functions, where non-linear functions utilized have been known as the gamma function where the mapping relationship is X raised to the power of gamma. i.e., the X (the sensor output value to be mapped to the display) is the base numeral. While the linear and the gamma functions have been well known in the art for many years, they have some drawbacks.
A single aspect linear mapping approach will, by design, result in a loss in image dynamic range across the entire display, thereby eliminating some of the benefits of a higher dynamic range imaging sensor. The gamma function can be problematic in that either it often is too similar to the linear mapping approach with its concomitant problems, or it is prone to saturation where dynamic range is not degraded, but entirely lost.
Also in the past, it has been known to provide pilots or airborne refueling personnel, who are provided with a live video image, with a mere brightness adjustable display which allows an adjustability of the brightness of the incoming video image. In such displays, the mapping scheme is not believed to be altered other than a gain increase or decrease of brightness on every pixel.
Consequently, there exists a need for a system for airborne personnel to be able to view and have the ability to benefit from live, high-dynamic range video images on a low-dynamic range display.